Power-driven hammer or riveter



Jan. 3, 1928.

J. C. BARRETT POWER DRIVEN HAMMER 0R RIVETER' Filed Aug. 6. 1925 2 Sheets-Sheet 1 Jan; 3, 1928. 1,654,571

J. C. BARRETT POWER DRIVEN HAMMER 0R RIVE'IER Filed Aug. 6. 1925 2 Sheets-Sheet 2 INVENTOR I ATTORNEY Patented Jan.

JQSEPH C. BARRETT, OF OCEANSIDE, NEV] ATENT, QFEIEML.

YORK, .ASSIGNOR TO AJAX ELECTRIC HAM- lfilEBi COEIOEAIION, OF NEW YORK, N. Y., A CORFORATIGN OF NEVIYORK.

POWER-DRIVEN HAMMER QB, BIVETER.

Application filed August 6, 1925. Serial No. 48,689.

This invention relates to power driven hammers or riveters and especially a ham mer or riveter particularly adapted to electrio of other rotary motor drive.

The object ot. the invention generally is a rotary motor driven hammer or riveter in which .he rotary motion is converted into hammer or riveting thrusts with peculiar smoothness andefliciency in operation and with marked freedom t in shock to the operator and wear upon the hammer mechanism, and which is further characterized by its reliability in service, its durability and its ability to stand up under the severe service operating conditions to which it is subjected.

To these ends I have devised a rotary driven power hannner including a double cam and rotary drive mechanism by which is effected a positive mechanical drive of the hammer throughout the greats portion of.

the thrust stroke and with a gradually increasing acceleration of the hammer, but with a complete cessation of the mechanical drive and power connection during a definite appreciable part of the cycle at the end of the thrust stroke, including the moment of impact, and whereby during the cessation of the ntiechanieal drive the momentum of the hammer element carries the latter in advance of the rotary drive to deliver the impact free from any driving or binding connection with the rotary drive and whereby the pick-up of the-hammer element by the laggingrotary drive at the beginning of the lifting stroke is effected in a sure and certain manner and without undue binding or strains upon any part of the mechanism, notwithstanding substantial variations in the length of the thrust stroke. My invention also includes-a special arrangement of thrust cam rotary drive and thrust roller guides whereby the gradual acceleration off the hammer during the thrust stroke is effected in a particularly eflicient and effective manner. p

For a better understanding of the above indicated features of the invention and others which will hereinafter appear, reference may be had to the accompanying drawings forming a part of this application wherein Fig. 1 is a side elevation of a hammer structure embodying my invention with a part of the casing removed,

is a similar View thereof at right Fi e Fig. 3 is a section along the line 33 of 1, v I 7 Figs. 4-9 inclusive are diagrammatic views illustrating the functioning of the structure shown in Figs. 1 to 3, and

Fig. 10 is a diagrammatic view of a moditied double cam structure. Referring to the drawings where likenumorais designate similar parts throughout, I have indicated my novel power hammer or riveter as comprising a main frame-consisting of the casing part 1 which is adapted to receive a suitable power drive, as for example an electric motor (not shown for convenience in illustration), apart'2 containing the drive mechanism which is interposed betweenthe power motor and the hammer, and casing element 8 for guiding the'hammer element 4} in its reciprocating movements. The casing parts 1 and 2 are preferablyintegrally formed of a single casting and a cover plate 2 for the part 2 is attachable to the frame part 2 by means of suitable bolts passing through the bolt holes 5. The r0- tary drive includes generally a rotary driving member or turret 6 which is journaled in the casing part 2, as for example by means oi a ball bearing unit 7, the rotary n'iember 6 being carried on the end of a shaft '6 andthe latter being suitably journaled in the casin part 2. Between this rotary member 6 and .themotor shaft 8 isinterposed a suitable drive including aworm 9 on shaft 8 and a worm gear 10 carried by the rotary member 6. I The casing part 2, 2 for the drive is adapted to contain a suitable lubricant and cover lids 11 are provided for inspection or introduction of the lubricant. The hammer element 4 is reciprocable in the direction of the arrow shown and carries integrally or rigidly therewith a slide block 12, the slide block 12 being laterally guided by the pair of thrust rollers 13, while the hammer head i is guided in any suitable 111.21111161,-1S for example within the chamber of casing part 3. The rotary drive member 6 is conveniently journ'aled so as to have its side surface approximately flush with or slightly below the face of the casing part 2 and the latter serves as a convenient seat for theslide block 12 which functionswith a driving crank pin 14 carried by the mem- 6 to effect reciprocationot the ammer :nent the crank pin member i4 carrying;

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a rotary sleeve 14. In the particular embodiment of my invention herein exhibited the rotary elrive consists of a single rotary member 6 and pin 14, and the latter functions with a double cam carried by the slide block 12, and preferably integrally formed therewith, to effect the reciprocation of the hammer. This double cam includes a convex cam 15 and a concave cam 16, and on the Withdrawal or lifting stroke of the hammer the rotating pin 14: is adapted to engageand follow the cam 15, while by engaging and following the other cam 16 the rotary drive.

imparts the thrust stroke to the hammer. The special consri ction'and arrangement of the-hamn'ier and drive whereby 1 effect the hammering and riveting operation of the superior'character indicated above, will be ap parent upon reference to Figs.19 inclusive, which figures are more or less diagrammatic and show the construction on a larger scale. 1 indicates the relative position of the parts o'f' the mechanism during the lifting-or withdrawing stroke of the hammer wherein the driving pin or roller 14 is in engagement with the lifting convex cam 15 andin a position to impart the maximum lifting or Withdrawing speed to the hammer." After this maximum lifting speed is reached the speed of the driving crank pin 1 i'in 'the direction of the lift stroke begins to decrease and the hammer is gradually brought to rest by the retarding action of the cam 16 bearing against the roller pin 14:. Fig. 5 indicates approximately the maximum lift position of the hammer with thedriving pin 1 1 engaging the'concave cam '16 to initiate the'thrust stroke'o f the hammer, and Fig. 8 indicates the thrust stroke completed and. the driving pin 14 initially engaging the convex cam to'initiate 'theliftingstroke. The xis of rotation of the rotary drive member 6 is indicated at '17 and is preferably approximately in line with the centers of the thrust rollerslg. In the preferred embodiment illustratedboth the cams 15and 16 are of true areuate form with their active aiicl eif'ectiv'e surfaces havinga common cent-er at 18, but it understood that these cams may be of anysuitable construction and especially that they may depart from the true arcuate 01311 so long as they conform generally'to that character. The wordar'cuate as used hereinafter is understood therefore to include all" forn1s of "the general character of thetrue 'arc'uate construction, whether conforming exactly thereto or not. The arrangement is'sueh that the'cen'ter of revolution 18 ofthe c am surfaces off-set laterally to one sideot' the axis 17 of the rotary member 6, and according to the embodiment herein exhibited distance approximately equal to the radius of the circular'pathtraveled by thee-enter of the drive'rollerla Forcona substantial lost motion or lateral play between the driving roller 14 and the coopei'ating cam surfaces 15 and 16 with which itelterna'tely engages. For example, this lost motion or relative lateral playbetween the eccentric and the cams, as indicated in 8, is shown between the lines 19, the radius of curvature of the cam lfi being greater at this point than. the sum of the corresponding radii of the cam15 and the diameter of the driving roller pin 14, while,

as indicateddn 7, this lost motion or play s ndicated by the distances between the'lines 19 which are drawn on both sides of the driving roller. One purpose of this lost mot on connection or lateral play and unimpeded opening or chan'iber above is to permit the hammer element and the slide block 12 to be carried forward. a substantial distance in advance of the driving pin 14rwhen near the end of the thrust stroke without fouling or binding against the rotary pin i l or any other part of the structure andto permit the pin to continue its arcuate path without binding in anypracticable position the hammer inlay assume at the impact. For example, referring to Fig. '7, which indicates the probable approximate positions of the hammer i'nechanism at the initial impact, the lost motion or play in dicated betw'een'the lines 19 on both sides ofthe driver 1 1 has permitted the hammer element to be carried forward in advance of 'the moving driving roller, and permits the latterto continue its arcate path'to pick up the hennner without binding against the cam 16 in the event that the hammer elen'ient /i not permitted to continue throughout its complete thrust stroke, as for e'L-iainple on meeting some obstruction. The relative arrangen'ieiit of the rotary drive member 6,:the driving roller 1e and the-double cam must be such that at the beginning of the lifting stroke the eccentric 14% en gages the curved surface ofthe Cain at a point and with the thrust in such direction as to impart to th e hammer a force with liftingcomponent. 'i lie lost motion connect -ion above referred to' a id the particular construction and reiatii'e arrangementof camsurface insect this purpose. l or example as indicated in'Figsl 'i" and 8, the driver 14; is freeto advance through ts ar cuate path without binding the cam 16 while tliehan'imerelement is resting at the end of the thrustfstroke, andengagesthe earn at tlle lllltltzl rifting movement at a point wherethe tangent to the cam surface forms less than a right an le with the horizontal,

the driving pin 14 being permitted to. engage the cam 15 at a point low enoughto effect not only a lateral thrust but a lifting component with the hammer in its further-most thrust position. I have indicated at 20 the tangent as being d'awn at approximately the point of the initial lifting engagement. This is the approximate point .ofinitial lifting engagement at the end of the maximum thrust stroke, but of course this point would be advanced further underneath the lifting cam 15 if the hammer should, at that instant, be slightly withdrawn from the impact object, as for example in the position shown in Fig. 7. The construction and arrangement of the mech anism is also such that the side thrust-of the driving pin 14 is always approximately in the direction of a thrust roller 18, and particularly the arrangement of the cam 16, the driving eccentric and the thrust roller 13 adjacent thereto is such that beginning with the initial thrust stroke movement indicated in Fig. 5, for every unit movement of the driving pin 14; about its arcuate path there is a corresponding linear thrust movement of the hammer Which gradually increases towards the end of thethrust stroke. For example in the particular embodiment of the invention herein exhibited, starting with a substantially Zero linear thrust movement of the hammer for a unit arcuate movement of the center of the driving pin l t'at the position indicated in Fig. 5, this linear thrust movement of the hammer gradually increases until the corresponding thrust movement or speed of the hammer approaching the end of the thrust stroke is considerably more than the linearcomponent of the speed of the center of the driving roller let in the direction of thrust, and in the partic ular embodiment herein exhibited, the hamin'er speed increases to a point where it is more than twice such speed of the driving roller. In the preferred arrangement, this maximum speed ofthe hammer in the thrust direction is attained just prior to the driver 14 reaching a position substantially in line with its center of movement and the adjacent thrust roller 13, the exact relative positions varying, of course, with the different relative arrangements of driving mechanism. 1 have roughy indicated such position in-Fi 6 where the driver 14 is just approaching its maximum linear speed in the directionof thrust, and the cam 16 on one side and the straight side of the slide block 12 on the other side are being squeezed between the driver and the adjacent thrust roller 13, theta (6) indicating the angle between the side of the guide block 12 and the tangent to the cam 16 at the point where the driver 14: engages therewith. The gradually increasing speed. of the hammer in the thrust direction, the driver 1 1 rides .up the concave cam 16, up tothe point where its speed is greater than the linear component of the driver 14 in the thrust direction, results in the advance of the hammer by reason of its own momentum forward and ahead of the driver letwhen approaching the end, of the stroke, sothat in some such position as that indicated roughly in Fig. 6 the hammer 4: is carried forward by its own momentum to effect the impact of the hammer entirely free of the rotary drive, the doublecam being constructed and arranged'as above described to clear the driver when impact occurs. This arrangement while permitting thejfree and unhindered independent forward and variable movements of the hammer with reference to the driving mechanism does not impair the positive mechanical driving connections during both the lifting and the thrust strokes, so that a particularadvantage of my power hammer is that while 1 effect the positive mechanical driving connection between the rotary eccentric and the hammer during the forward and backward strokes, yet at an appreciable time before the actual impact of the hammer and during a considerable period thereafter in each cycle of operation there is no mechanical or binding connection between the hammer element and the rotary drive. This insures the reduction to a. minimum of shocks, vibrations and wear, and moreover the easy unbinding, pick up after each hammer stroke, the easy and gradual lift and reversal at the end of the lifting stroke and the generally smooth operation contribute to endurance and reliability in operation. Fig. 9 indicates the essential active parts in this embodimentof the cams 15 and 16 at the trailing or thrust end thereof, namely those parts with which the driver let actually engages during op- (31.3lii011. That part of the cam 16 above the line 21 appears to be active only at low speeds (starting and stopping), it being found in practice that substantially nowear occurs on that part, indicating that at high speeds the hammer moves ahead of and out of engagement with the driving roller 14 when the latter reaches this point of the cycle.

In the particular embodiment shown the relative lost motion or play between the driving eccentric and the double cam continues throughout the active portions of both cams, this being desirable for practical;

constructional reasons, but it is understood that at the ends of the double cam corre- CERTIFICATE 0F CQRRECTEON.

Patent No. 1,654,571, Granted Januar y 2,, .1928, w

mm; 0. mmm's.

it is hereby certified that eamr appears in fine printed specification 0% the abuve numbered patent requiring correctim as iu-Haws: Page 4, line 77, claim 7 and M11684, claim 8, for the numeral 5" mad "1"; and that the said Letters Patent sheufid be read with these (finest-isms tmrein that the same may cenfim'm to we reem'd 0? the case in the Eaaent fi'ifiice. I

Signed and seamed this 14th day 0% Eabmary, A. D. 1928.

M. J. MOMG,

Sea. Acting Commissioner of Patents. 

